1. Field of Invention
The invention relates to methods and devices usable to place a stent in an anatomical constricting structure, such as, for example, a sphincter, using an easily-inserted and easily-withdrawn, self-stabilizing stent.
2. Description of Related Art
Prostheses usable to provide an artificial passage in anatomical tracts, such as, for example, the urinary, respiratory, digestive, gynecological or vascular tracts, in a living being are known. For example, an endo-urethral prosthesis for a human is known to have a tubular element whose walls are made from a relatively smooth and soft bio-compatible material, for example a silicone rubber, at least in its outer part. Such a tubular element is sufficiently flexible to conform to the anatomical profile and movements of, for example, a human urethra, while providing sufficient rigidity that the tubular element will not collapse under the influence of the anatomical profile or movements of the urethral tract.
As disclosed in FR-A-2 667 783, a tubular element, as described above, is placed in the urethra without passing through the striated muscles that form the sphincter in the urethral tract. The tubular element is supported primarily by the elasticity of the tubular element and the compressive force of the urethral wall. If the tubular element""s diameter is large enough, the compressive forces of the elastic urethral wall may adequately secure the tubular element in the urethral tract. However, if the tubular element is too large, damage to the urethral wall may occur and withdrawal of the tubular element may be painful to the patient.
Alternatively, a smaller-diameter tubular element may be used, with notches formed in the outer wall of the tubular element, to provide a degree of secondary support for the tubular element within the urethral tract. However, such notches do not prevent the tubular element from moving downward, or descending, in the urethra during micturition, for instance. The changing position of the tubular element renders the tubular element problematic and risks discomfort to the patient. Further, providing the tubular element with scales, or fastening catches, to counter the tendency of the prosthesis to descend during micturition does not prevent the prosthesis from moving upward, or ascending, in the urethral tract as a result of routine bodily motions or functions. Such scales, or fastening elements also generate increased discomfort to the patient during withdrawal of the tubular element.
Other known catheter-delivered prostheses that provide an artificial passage in an anatomical tract of a living being include very flexible, spirally coiled metal elements. However, the flexible quality of the spirally coiled elements prove very unstable during insertion as the more rigid delivery catheter ends where the flexible element begins. As a result, bunching or other inappropriate placement of the flexible member often occurs, requiring withdrawal and re-insertion of the prosthesis, and/or causing discomfort to the patient due to the ill-configured element.
Still other known catheter-delivered prostheses that provide an artificial passage in an anatomical tract of a living being require ultra-sound, radioscopy, or other indirect visualizing devices to determine when and whether the prosthesis is in position to provide the artificial passage desired without inhibiting the natural constricting function of the anatomical constricting structure against the anatomical tract.
Thus, known tubular element prostheses are not self-stabilizing across a anatomical constricting structure. Nor are known prostheses provided with a method for inserting the prosthesis into and withdrawing the prosthesis from an anatomical tract that minimizes the pain and discomfort typically associated with stenting. Similarly, known prostheses do not have structures that provide a direct method for determining whether the catheter-delivered prosthesis is in the appropriate position in the anatomical tract such that the artificial passage is created without inhibiting the natural constricting function of the anatomical constricting structure against the anatomical tract.
This invention provides stent assemblies and methods usable to insert and withdraw a self-stabilizing prosthetic stent to or from an anatomical tract of a living being.
This invention separately provides stent assemblies and insertion/withdrawal methods that allow the self-stabilizing prosthetic stent to create an artificial passage within the tract in a manner that minimizes pain and discomfort to the living being.
This invention separately provides stent assemblies and insertion/withdrawal methods that enable a user to determine directly when the self-stabilizing prosthetic stent is properly placed.
In various exemplary embodiments, the self-stabilizing prosthetic stent comprises distal and proximal segments connected to one another via a flexible connection structure to form an approximately continuous outer surface of the self-stabilizing prosthetic stent. The approximately continuous outer surface of the self-stabilizing prosthetic stent permits non-traumatic insertion or withdrawal of the self-stabilizing prosthetic stent to or from an anatomical tract of a living being without needing anesthesia. In various exemplary embodiments, the distal and proximal segments are generally tubular elements that can be formed of a relatively smooth, soft bio-compatible material. This permits the distal and proximal segments to conform to the profile and movements of the anatomical tract that the self-stabilizing prosthetic stent is placed within. In various exemplary embodiments, each of the distal and proximal segments have a substantially constant cross-section.
In various exemplary embodiments, the self-stabilizing prosthetic stent""s flexible connection structure includes a tubular, flexible sleeve having opposed first and second ends. The first end of the flexible connection structure connects to the self-stabilizing prosthetic stent""s distal segment. The second end of the flexible connection structure connects to the self-stabilizing prosthetic stent""s proximal segment. The flexible connection structure, when properly seated, lies adjacent to the anatomical constricting structure of the anatomical tract. The flexible quality of the flexible connection structure permits the natural function of the anatomical constricting structure to continue, thus creating the desired artificial passage in the anatomical tract.
In various exemplary embodiments, the stent assembly usable to insert and withdraw this self-stabilizing prosthetic stent structure includes one or more additional structural features permitting the insertion and withdrawal methods of the invention to be achieved.
In various exemplary embodiments, inserting the self-stabilizing prosthetic stent uses a delivery catheter, on which at least a portion of the self-stabilizing prosthetic stent is placed, to generally guide the self-stabilizing prosthetic stent into an anatomical tract. In various exemplary embodiments, the delivery catheter includes a semi-rigid, hollow mandrel usable to urge the distal stent segment into the anatomical tract, and a pusher to push the proximal stent segment, in a trailing fashion relative to the distal stent segment, to the desired position within the anatomical tract.
In these exemplary embodiments, the pusher is first placed upon the mandrel. The self-stabilizing prosthetic stent is then mounted upon the mandrel. The self-stabilizing prosthetic stent is then placed into the anatomical tract such that a generally closed end of the distal stent segment enters the anatomical tract first. The flexible connection structure joins the distal stent segment to the proximal stent segment and also is mounted upon the mandrel. Mounting the self-stabilizing prosthetic stent in this manner upon the mandrel precludes the flexible connection structure from deforming until after the mandrel is withdrawn. The hollow mandrel is provided with an opening on one end that aligns with a similar opening in the closed, rounded end of the distal stent segment. Aligning the openings in the mandrel and the distal stent segment permits fluid to flow into and through the self-stabilizing prosthetic stent and mandrel.
Together, the mandrel and the pusher advance and maintain the self-stabilizing prosthetic stent, particularly the distal stent segment, into a desired position relative to a target organ and/or body cavity as the stent assembly delivers the self-stabilizing prosthetic stent into and through the anatomical tract, and ultimately to the target organ and/or body cavity. An end of the proximal segment of the self-stabilizing stent, furthest from the flexible connection structure, is provided with an eyelet from which one or more withdrawal threads, pull-wires, or equivalent structures extend outwardly through the anatomical tract to be accessible outside of the living being.
Combined with the delivery catheter, the self-stabilizing prosthetic stent is inserted to the desired anatomical tract until the proximal and distal segments of the self-stabilizing prosthetic stent extend at least partly across an anatomical constricting structure and until the closed end of the distal segment reaches a desired position relative to the target body cavity or organ, such as, for example, extending into a bladder. The openings in the distal segment""s closed end and in the mandrel are aligned such that a flow of fluid through the self-stabilizing prosthetic stent and in the mandrel occurs, signaling that the self-stabilizing prosthetic stent has reached a desired location relative to the target organ and/or body cavity. Thus, general placement of the self-stabilizing prosthetic stent is achieved without needing ultrasound, radioscopy, or other visualizing methods or devices.
The mandrel is then withdrawn, while the pusher is maintained in place. Once the mandrel is withdrawn, the flexible connection structure is available and will flex in response to the natural constricting or relaxing functions of the anatomical constricting structure. Then, the pusher is withdrawn. The one or more withdrawal threads, pull-wires, or other equivalent structures that extend from the self-stabilizing prosthetic stent is accessible outside of the living being. At least one of the withdrawal threads, pull-wires, or other equivalent structures is then gently tugged until the flexible connection structure of the self-stabilizing prosthetic stent is fully extended and seated within the anatomical constricting structure.
Thus, specific placement of the self-stabilizing prosthetic stent and the flexible connection structure is easily identified as increased resistance to tugging on the at least one withdrawal thread, pull-wire, or other equivalent structure is sensed when the flexible connection structure is seated in the anatomical constricting structure. Further, the natural function of the anatomical constricting structure causes the flexible connection structure to close, thus stopping the flow of fluid through the self-stabilizing prosthetic stent and directly indicating that the self-stabilizing prosthetic stent is appropriately positioned within the anatomical tract. Accordingly, an artificial passage, complying with the natural functions and configurements of the anatomical tract, is achieved.
Withdrawing the self-stabilizing prosthetic stent is accomplished by providing a more constant pulling on at least one of the withdrawal threads, pull-wires, or other equivalent structures of the self-stabilizing prosthetic stent so that the constricting forces of the anatomical constricting structure are overcome. Having overcome the anatomical constricting forces, the self-stabilizing prosthetic stent can be freely removed from the anatomical tract with reduced pain or discomfort.
In other exemplary embodiments of the stent assembly and insertion and withdrawal methods of this invention, the self-stabilizing prosthetic stent is mounted upon a delivery catheter. In various exemplary embodiments, the proximal and distal stent segments abut one another during insertion due to the flexible connection structure joining the distal and proximal stent segments being in a collapsed state. An end of a distal stent segment release structure protrudes through a wall of the delivery catheter to hold the distal stent segment in place during insertion. The distal stent segment has a generally closed end that is placed relative to a target organ and/or cavity, and an opening through which fluid flows when the self-stabilizing prosthetic stent reaches the target organ or body cavity. A stiff member is used during insertion of the self-stabilizing prosthetic stent to position the distal segment of the self-stabilizing prosthetic stent, or to more securely maintain the position of the distal segment in the anatomical tract and relative to the target organ and/or body cavity.
An end of a proximal stent segment release structure protrudes through the wall of the delivery catheter to hold the proximal stent segment in place during insertion, such that the proximal and distal stent segments are maintained in an abutting relationship during insertion until the respective release structures are withdrawn. Fluid flow through the opening in the generally closed end of the distal stent segment signals that the self-stabilizing prosthetic stent has reached the target organ and/or body cavity. The distal stent segment release structure, the proximal stent segment release structure, and the delivery catheter are removed in any one of a number of different orders, depending on which exemplary embodiment is being used, to seat the flexible connection structure of the self-stabilizing prosthetic stent in the anatomical constricting structure.
Proper positioning of the flexible connection structure is easily detected as the fluid flow from the target organ through the self-stabilizing prosthetic stent and the delivery catheter ceases as the flexible connection structure extends such that the proximal and distal stent segments no longer abut one another. By seating the flexible connection structure of the stent in the region of the anatomical constricting structure, the natural functioning of the anatomical constricting structure is permitted and the desired artificial passage in the anatomical tract is achieved.
In still other various exemplary embodiments, the proximal and distal stent segments, in a non-abutting relationship to one another, are mounted upon a hollow delivery catheter such that the flexible connecting structure joining the proximal and distal stent segments is substantially extended during insertion of the stent to the anatomical tract. Fluid flow through the hollow delivery catheter and stent again indicates the stent has reached the target organ and/or body cavity. Withdrawal of the delivery catheter permits the natural constricting and relaxing functions of the anatomical constricting structure to act upon the flexible connecting structure of the stent. Again, gentle tugging on at least one of the one or more withdrawal threads, pull-wires, or other equivalent structures enable the flexible connecting structure to be seated more compliantly with the anatomical constricting structure desired.
Withdrawing the self-stabilizing prosthetic stent is accomplished by providing a more constant pulling on at least one of the one or more withdrawal threads, pull-wires, or other equivalent structures so that the constricting forces of the anatomical constricting structure are overcome. Having overcome the anatomical constricting forces, the self-stabilizing prosthetic stent is freely removable from the anatomical tract.
It should be appreciated that in all of the exemplary embodiments the self-stabilizing prosthetic stent may also be used to instill fluids, or other irrigating solutions, to the target organ and/or body cavity. Further, the stent assemblies and stent insertion and withdrawal methods according to this invention may be used to insert or control other instruments, such as, for example, an endoscope, to view or otherwise involve a target body cavity or organ by deploying an instrument through the stent assembly and self-stabilizing prosthetic stent using the methods described.
It should be further appreciated that, in all of the exemplary embodiments, the flexible connecting structure may be tubular, threaded, slotted, or any equivalent structural combination permitting the seating of the flexible connecting structure for compliance with the naturally occurring actions within the anatomical constricting structure the flexible connecting structure is subject to, such as, for example, the structures disclosed in the incorporated U.S. Pat. No. 5,766,209.
It should be still further appreciated that the terms xe2x80x9cdistalxe2x80x9d and xe2x80x9cproximalxe2x80x9d as used herein are exemplary only with reference to the insertion entry point of the self-stabilizing prosthetic stent after the self-stabilizing prosthetic stent is inserted into the anatomical tract.
The simplicity of the insertion and withdrawal methods and structures according to this invention permit non-specialists to place successfully a stent in a living being relatively painlessly, and without needing anesthesia. Further, appropriately positioning the self-stabilizing prosthetic stent can be achieved without expensive visualizing equipment, because the appropriate placement of the self-stabilizing prosthetic stent across the anatomical constricting structure is determined directly based on the flow of fluid or gases through the self-stabilizing prosthetic stent, by feeling the resistance to further withdrawal of the stent, and/or by the living being controlling, for example, micturition by voluntarily controlling, for example, the sphincter across which the flexible connecting structure of the self-stabilizing stent is placed.
These and other features and advantages of this invention are described in, or are apparent from, the detailed description of various exemplary embodiments of the systems and methods according to this invention.